System and method for controlling temperature of a working fluid

ABSTRACT

A heat exchanging device is presented. The heat exchanging device includes an inlet header configured to receive a working fluid. Further, the heat exchanging device includes at least one coil segment having a first end and a second end, where the first end of the at least one coil segment is coupled to the inlet header and configured to receive the working fluid from the inlet header. In addition, the heat exchanging device includes an outlet header coupled to the second end of the at least one coil segment and configured to receive the working fluid from the at least one coil segment. Also, the heat exchanging device includes at least one propeller disposed proximate to the at least one coil segment and configured to propel subsea water across the at least one coil segment to control a temperature of the working fluid in the outlet header.

BACKGROUND

Embodiments of the present disclosure relate generally to a subsea heatexchanger, and more particularly to a system and method for controllingtemperature of a process or working fluid in subsea equipment.

Typically, one or more products, such as oil, natural gas, or acombination of the two are extracted from subsea wells and processed onan ocean bed. Further, these products may be used as working fluids forone or more applications. However, the products that are extracted fromthe subsea wells may have a very high temperature, and processing theseproducts at this high temperature is challenging. In one example, thetemperature of these products may be in a range from about 80 degrees toabout 200 degrees. Thus, it is important to control the temperature ofthe products prior to processing the products on the ocean bed.

In conventional systems, one or more heat exchangers may be usedunderwater to regulate or control the temperature of the products thatare extracted from the subsea wells. These heat exchangers may leveragesubsea water to cool these products. Typically, the subsea water mayhave a temperature that is relatively lower than the temperature of theproducts. Also, the subsea water may have high heat capacity that aidsin controlling or absorbing heat from the products. However, these heatexchangers depend upon natural or free convection of the subsea water tocool the products. Also, as the temperature of these products is veryhigh, a large amount of heat needs to be dissipated from the products.Hence, dissipating heat from these products calls for the use of heatexchangers with a large heat transfer area. In addition, as these heatexchangers rely upon natural or free convection with its inherent lowheat transfer coefficient, the size tends to be further increased. As aresult, these large heat exchangers are very expensive to manufacture.In addition, these heat exchangers tend to be bulky and are difficult tomove to a location on the ocean bed or seabed.

BRIEF DESCRIPTION

In accordance with aspects of the present disclosure, a heat exchangingdevice is presented. The heat exchanging device includes an inlet headerconfigured to receive a working fluid. Further, the heat exchangingdevice includes at least one coil segment having a first end and asecond end, where the first end of the at least one coil segment iscoupled to the inlet header and configured to receive the working fluidfrom the inlet header. In addition, the heat exchanging device includesan outlet header coupled to the second end of the at least one coilsegment and configured to receive the working fluid from the at leastone coil segment. Also, the heat exchanging device includes at least onepropeller disposed proximate to the at least one coil segment andconfigured to propel subsea water across the at least one coil segmentto control a temperature of the working fluid in the outlet header.

In accordance with further aspects of the present disclosure, a methodfor controlling a temperature of a working fluid is presented. Themethod includes directing, by at least one coil segment, working fluidfrom an inlet header to an outlet header in a heat exchanging device.Also, the method includes determining, by a control unit, a temperatureof the working fluid in the outlet header. Further, the method includespropelling, by at least one propeller, subsea water across the at leastone coil segment to control the temperature of the working fluid in theoutlet header.

In accordance with another aspect of the present disclosure, a system ispresented. The system includes an inlet header. Also, the systemincludes an outlet header. Further, the system includes a plurality ofcoil segments disposed between the inlet header and the outlet headerand configured to direct working fluid from the inlet header to theoutlet header. In addition, the system includes a plurality ofpropellers disposed proximate to the plurality of coil segments andconfigured to propel subsea water across the plurality of coil segmentsto control a temperature of the working fluid in the outlet header.

DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a diagrammatical representation of one embodiment of a heatexchanging device, in accordance with aspects of the present disclosure;

FIG. 2 is a diagrammatical representation of another embodiment of aheat exchanging device, in accordance with aspects of the presentdisclosure;

FIG. 3 is a diagrammatical representation of a propeller disposed in anozzle, in accordance with aspects of the present disclosure;

FIGS. 4-7 are diagrammatical representations of different embodiments ofa coil segment for use in a heat exchanging device, in accordance withaspects of the present disclosure; and

FIG. 8 is a flow chart illustrating a method for controlling temperatureof a working fluid, in accordance with aspects of the presentdisclosure.

DETAILED DESCRIPTION

As will be described in detail hereinafter, various embodiments ofexemplary systems and methods for controlling temperature of a workingfluid are presented. By employing the methods and the variousembodiments of the system described hereinafter, the working fluid maybe cooled at a very low cost.

Turning now to the drawings and referring to FIG. 1, a diagrammaticalrepresentation of a heat exchanging device 100, in accordance withaspects of the present disclosure, is depicted. The heat exchangingdevice 100 may be used for underwater applications to control atemperature of a working fluid that is extracted from subsea wells. Inone example, the working fluid may include well products, such as gas,liquids, and/or water. In another example, the working fluid may be anycoolant that is used to cool components, such as a motor in subseaequipment. The working fluid may have a temperature that is in a rangefrom about 80 degrees to about 200 degrees. As will be appreciated,processing or using the working fluid at these high temperatures may bea challenging task. In accordance with aspects of the presentdisclosure, the heat exchanging device 100 may be employed to controlthe temperature of the working fluid.

In a presently contemplated configuration, the heat exchanging device100 may include an inlet header 102, one or more coil segments 104, anoutlet header 106, one or more propellers 108, and a control unit 110.In one embodiment, the one or more coil segments 104 may be disposedbetween the inlet header 102 and the outlet header 106. In theembodiment of FIG. 1, four coil segments 104 are positioned between theinlet header 102 and the outlet header 106. Each of the coil segments104 may include a first end 112 and a second end 114. The first ends 112of the coil segments 104 may be coupled to the inlet header 102, whilethe second ends 114 of the coil segments 104 may be coupled to theoutlet header 106. It may be noted that the coil segments 104 mayinclude a bundle of coils that are arranged in one or more determinedpatterns. These patterns will be described in greater detail withrespect to FIGS. 4-7. Also, the inlet header 102 and the outlet header106 may be referred to as channels that are used for circulating theworking fluid through the bundle of coils in the coil segments 104. Itmay be noted that the heat exchanging device 100 may have any number ofcoil segments, and is not limited to the number of coil segments shownin FIG. 1.

As depicted in FIG. 1, the inlet header 102 may be configured to receivethe working fluid from an external unit (not shown). The receivedworking fluid may be distributed equally through each of the coilsegments 104. The working fluid may be channeled through each of thecoil segments 104 and collected by the outlet header 106. Further, theoutlet header 106 may be configured to route the collected working fluidback to the external unit. In one embodiment, the external unit mayinclude one or more components, such as a subsea motor or a compressorin subsea equipment (not shown).

In conventional systems, heat exchangers employ natural or freeconvection of the subsea water to transfer heat from the working fluidto the subsea water. However, these heat exchangers are large in size asthey rely on natural or free convection of the subsea water to cool theworking fluid. Also, the conventional systems entail use of a greaternumber of heat exchangers for dissipating the heat from the workingfluid. Moreover, these large heat exchangers are very expensive tomanufacture and difficult to move to a location on the ocean bed orseabed.

To overcome the above shortcomings, in one exemplary embodiment, theheat exchanging device 100 may employ the one or more propellers 108 toforce the flow of the subsea water across the coil segments 104, ratherthan relying on the natural or free convection of the subsea water. Thisforced flow of the subsea water may enhance the external heat transfer,thus increasing the transfer of heat from the working fluid to theseawater, and thereby aid in controlling the temperature of the workingfluid.

As depicted in FIG. 1, each of the propellers 108 may be disposedproximate to a corresponding coil segment 104. In one embodiment, thesepropellers 108 may be operated at a fixed speed. Further, the propellers108 may be configured to propel the subsea water across the coilsegments 104. More particularly, the subsea water may be forced to flowacross the coil segments 104. This forced flow of the subsea water inturn aids in transferring the heat from the working fluid that isflowing within the coil segments 104 to the surrounding seawater.

Furthermore, the control unit 110 may be configured to regulate the flowof subsea water across the coil segments 104. More particularly, thecontrol unit 110 may be configured to activate or deactivate one or morepropellers 108 so as to regulate the flow of subsea water across thecoil segments 104.

In accordance with aspects of the present disclosure, the control unit110 may be configured to regulate the flow of the subsea water acrossthe coil segments 104 based on the temperature of the working fluid inthe outlet header 106. It may be desirable to maintain the temperatureof the working fluid within a determined temperature range. Thedetermined temperature range may have an upper bound and a lower bound,in one example. Accordingly, in one embodiment, the control unit 110 mayinclude a first sensor 116 and a processing subunit 118. The firstsensor 116 may be operatively coupled to the outlet header 106 andconfigured to determine the temperature of the working fluid at adetermined location in the outlet header 106. In one embodiment, thedetermined location may be a location in the outlet header 106, wherethe working fluid exits the outlet header 106. Further, the first sensor116 may be configured to communicate the determined temperature to theprocessing subunit 118.

Moreover, in accordance with aspects of the present disclosure, theprocessing subunit 118 may be configured to determine a number ofpropellers 108 to be activated and/or deactivated based on thetemperature of the working fluid in the outlet header 106. Inparticular, the processing subunit 118 may be configured to determinethe number of propellers 108 to be activated and/or deactivated based onan amount of heat to be dissipated from the working fluid. To that end,in one embodiment, the processing subunit 118 may be configured todetermine if the temperature received from the first sensor 116 liesoutside the determined temperature range. If it is determined that thetemperature of the working fluid received from the first sensor 116 liesoutside the determined temperature range, the processing subunit 118 maybe configured to activate or deactivate a determined number ofpropellers 108. In one example, if the received temperature is greaterthan the upper bound of the determined temperature range, the processingsubunit 118 may be configured to activate a first subset of thepropellers 108. In a similar fashion, if the received temperature isless than the lower bound of the determined temperature range, theprocessing subunit 118 may be configured to deactivate a second subsetof the propellers 108. In one embodiment, the processing subunit 118 maybe configured to activate or deactivate the one or more propellers 108by communicating a first control signal to a corresponding propeller.

In accordance with further aspects of the present disclosure, theprocessing subunit 118 may be configured to activate or deactivate thepropellers 108 based on a temperature of the subsea water. Particularly,if the temperature of the subsea water is greater than the temperatureof the working fluid then propelling this subsea water across the coilsegments 104 may further increase the temperature of the working fluid.Thus, it may also be desirable to activate or deactivate the propellers108 based upon the temperature of the subsea water.

Accordingly, in one embodiment, the control unit 110 may include asecond sensor 120 configured to determine the temperature of the subseawater. In one embodiment, the second sensor 120 may be disposed in thesubsea water. Further, the second sensor 120 may be configured tocommunicate the temperature of the subsea water to the processingsubunit 118. The processing subunit 118 may be configured to compare thetemperature of the subsea water with the temperature of the workingfluid. Further, the processing subunit 118 may be configured to transmita second control signal to one or more propellers 108 to activate asubset of propellers 108 if the temperature of the subsea water is lessthan the temperature of the working fluid in the outlet header 106.Otherwise, the processing subunit 118 may be configured to transmit athird control signal to one or more propellers 108 to deactivate thesubset of propellers 108. In one embodiment, the processing subunit 118may be configured to select the number of propellers 108 to be activatedor deactivated based on a difference between the temperature of thesubsea water and the temperature of the working fluid.

Thus, by employing the one or more propellers 108 and the control unit110, the heat exchanging device 100 may effectively control thetemperature of the working fluid. Also, the size and cost ofmanufacturing the heat exchanging device 100 may be substantiallyreduced as the heat exchanging device 100 is configured to rely on theforce flow of the subsea water across the coil segments 104 to dissipateheat or control the temperature of the working fluid.

Referring to FIG. 2, a diagrammatical representation of anotherembodiment of a heat exchanging device 200, in accordance with anotheraspect of the present disclosure, is depicted. In the embodiment of FIG.2, the heat exchanging device 200 includes coil segments 202 that areserially connected to each other. Particularly, in the embodiment ofFIG. 2, each of the coil segments 202 may have corresponding inlet andoutlet headers. An outlet header of one coil segment 202 may beoperatively coupled to an inlet header of an adjacent coil segment 202.More specifically, an inlet header 204 of a first coil segment 206 maybe configured to receive a working fluid from an external unit (notshown). Further, the received working fluid may be directed through thefirst coil segment 206. The outlet header 208 of the first coil segment206 may be configured to collect the working fluid from the first coilsegment 206 and route the working fluid to an inlet header 210 of asecond coil segment 212. In a similar manner, the working fluid may berouted from the second coil segment 212 to a third coil segment 214 andfurther to a fourth coil segment 216 via respective inlet and outletheaders. The working fluid may be collected by an outlet header 218 ofthe fourth or last coil segment 216. Further, the outlet header 218 ofthe fourth coil segment 216 may be configured to route the working fluidto the external unit. It may be noted that the coil segments 202 may bearranged in a variety of configurations, and the arrangement is notlimited to the arrangements shown in FIGS. 1 and 2. In addition, acontrol unit 226 may be coupled to propellers 228 and configured toregulate the flow of subsea water across the coil segments 202. Thecontrol unit 226 may include a first sensor 220, a processing subunit222, and a second sensor 224.

In this embodiment, the first sensor 220 of the control unit 226 may becoupled to the outlet header 218 of the fourth coil segment 216. It maybe noted that the first sensor 220 may be representative of the firstsensor 116 of FIG. 1. Also, the processing subunit 222 and the secondsensor 224 may be representative of the processing subunit 118 and thesecond sensor 120, respectively. In addition, propellers 228 may berepresentative of the propellers 108 of FIG. 1.

Referring to FIG. 3, a diagrammatical representation 300 of a propellerdisposed in a nozzle configured for use in the heat exchanging devices100, 200, in accordance with aspects of the present disclosure, isdepicted. Reference numeral 302 may be representative of one of thepropellers 108 of FIG. 1. In accordance with exemplary aspects of thepresent disclosure, the propeller 302 may be enclosed by a nozzle 306.The nozzle 306 may be configured to aid in directing the flow of thesubsea water towards a coil segment 304. The propeller 302 surrounded bythe nozzle 306 may be used to propel the subsea water across acorresponding coil segment 304 such that the subsea water may absorb theheat from the working fluid in the coil segment 304. This transfer ofheat from the working fluid may aid in reducing the temperature of theworking fluid. With the inclusion of the nozzle 306, the flow of subseawater may be further streamlined towards the coil segment 304. This inturn improves the efficiency of the propeller 302. Also, overallefficiency of a heat exchanging device, such as the heat exchangingdevice 100 may be improved. It may be noted that the coil segment 304may be representative of one of the coil segments 104 in FIG. 1.

As depicted in FIG. 3, the nozzle 306 may include an inlet 308 and anoutlet 310. The inlet 308 may be provided along a bottom surface of thenozzle 306, while the outlet 310 may be provided along a top surface ofthe nozzle 306. The top surface of the nozzle 306 may be representativeof a surface of the nozzle 306 that is disposed closer to the coilsegment 304, while the bottom surface may be representative of a surfaceof the nozzle 306 that is disposed away from the coil segment 304. Also,an aperture of the outlet 310 of the nozzle may be smaller than anaperture of the inlet 308 of the nozzle 306, in one embodiment.

Referring to FIGS. 4-7, diagrammatical representations of differentembodiments of a coil segment configured for use in the heat exchangingdevices 100, 200 of FIGS. 1-2, in accordance with aspects of the presentdisclosure, are depicted. In FIG. 4, reference numeral 400 may berepresentative of one coil segment, such as the coil segment 104 ofFIG. 1. The coil segment 400 may include a helix bundle of coils 402that may be coupled between an inlet header and an outlet header of theheat exchanging device 100. Particularly, this helix bundle of coils 402may have a first end that is coupled to the inlet header and a secondend that is coupled to the outlet header of the heat exchanging device100.

Moreover, in the example depicted in FIG. 5, a coil segment 500 mayinclude a bundle of vertical pipes or coils 502. Similarly, as depictedin FIG. 6, a coil segment 600 may include a horizontal inline bundle ofcoils 602. Furthermore, in FIG. 7, a coil segment 700 may include ahorizontal staggered bundle of coils 702.

Referring to FIG. 8, a flow chart illustrating a method 800 forcontrolling a temperature of a working fluid, in accordance with aspectsof the present disclosure, is depicted. For ease of understanding, themethod 800 is described with reference to the components of FIG. 1. Themethod begins at step 802, where the working fluid may be directed fromthe inlet header 102 to the outlet header 106. The one or more coilsegments 104 may be used to channel or direct the working fluid from theinlet header 102 to the outlet header 106. Particularly, the inletheader 102 may receive the working fluid from the external unit (notshown) and the working fluid may be distributed equally to the coilsegments 104. Thereafter, the outlet header 106 may collect the workingfluid from the one or more coil segments 104 and route the working fluidto the external unit.

Subsequently, at step 804, the temperature of the working fluid in theoutlet header 106 may be determined To that end, the control unit 110may be configured to determine the temperature of the working fluid inthe outlet header 106. Particularly, the control unit 110 may includethe first sensor 116 that is coupled to the outlet header 106. The firstsensor 116 may be configured to determine the temperature of the workingfluid in the outlet header 106. Further, the determined temperature ofthe working fluid may be communicated to the processing subunit 118 inthe control unit 110.

In addition, at step 806, the subsea water may be propelled across theone or more coil segments 104 to control the temperature of the workingfluid in the outlet header 106. To that end, the one or more propellers108 may be used to propel the subsea water across the coil segments 104.Specifically, the processing subunit 118 may be configured to activateor deactivate the one or more propellers 108 to regulate the flow ofsubsea water across the coil segments 104. In one example, if thetemperature of the working fluid is greater than an upper bound of adetermined temperature range, the processing subunit 118 may beconfigured to activate the one or more propellers so as to lower thetemperature of the working fluid to lie within the determinedtemperature range. Similarly, if the temperature of the working fluid isless than a lower bound of the determined temperature range, theprocessing subunit 118 may be configured to deactivate one or morepropellers so as to decrease the amount of heat removed by the heatexchanging device 100 and thus reducing the temperature of the workingfluid in the outlet header 106. In one embodiment, the processingsubunit 118 may be configured to select the number of propellers 108 tobe activated or deactivated based on the amount of heat to be dissipatedfrom the working fluid.

The various embodiments of the system and method aid in controlling thetemperature of the working fluid. Also, as the heat exchanging deviceemploys the propellers, the size and number of the heat exchangingdevices used to cool a working fluid may be substantially reduced. Thisin turn helps to simplify the transport and installation of the heatexchanging device at a desired location. Also, the manufacturing cost ofthe heat exchanging device may be substantially reduced.

While only certain features of the invention have been illustrated anddescribed herein, many modifications and changes will occur to thoseskilled in the art. It is, therefore, to be understood that the appendedclaims are intended to cover all such modifications and changes as fallwithin the true spirit of the invention.

1. A heat exchanging device, comprising: an inlet header configured toreceive a working fluid; at least one coil segment having a first endand a second end, wherein the first end of the at least one coil segmentis coupled to the inlet header and configured to receive the workingfluid from the inlet header; an outlet header coupled to the second endof the at least one coil segment and configured to receive the workingfluid from the at least one coil segment; and at least one propellerdisposed proximate to the at least one coil segment and configured topropel subsea water across the at least one coil segment to control atemperature of the working fluid in the outlet header.
 2. The heatexchanging device of claim 1, further comprising a control unitoperatively coupled to the at least one propeller and configured toactivate or deactivate the at least one propeller to regulate flow ofthe subsea water across the at least one coil segment.
 3. The heatexchanging device of claim 2, wherein the control unit comprises: afirst sensor operatively coupled to the outlet header and configured todetermine the temperature of the working fluid in the outlet header; anda processing subunit electrically coupled to the first sensor andconfigured to communicate a first control signal to the at least onepropeller when the temperature of the working fluid in the outlet headeris outside a determined temperature range.
 4. The heat exchanging deviceof claim 3, wherein the processing subunit is configured to communicatethe first control signal to the at least one propeller to activate ordeactivate the at least one propeller.
 5. The heat exchanging device ofclaim 3, wherein the control unit further comprises a second sensoroperatively coupled to the processing subunit and configured todetermine a temperature of the subsea water.
 6. The heat exchangingdevice of claim 5, wherein the processing subunit is configured to:compare the temperature of the subsea water with the temperature of theworking fluid in the outlet header; and communicate a second controlsignal to the at least one propeller to activate the at least onepropeller when the temperature of the subsea water is less than thetemperature of the working fluid in the outlet header.
 7. The heatexchanging device of claim 6, wherein the processing subunit isconfigured to transmit a third control signal to the at least onepropeller to deactivate the at least one propeller when the temperatureof the subsea water is greater than the temperature of the working fluidin the outlet header.
 8. The heat exchanging device of claim 1, whereinthe outlet header is configured to supply the working fluid receivedfrom the at least one coil segment to an external device.
 9. The heatexchanging device of claim 1, further comprising a nozzle enclosing theat least one propeller and configured to streamline a flow of the subseawater towards the at least one coil segment.
 10. A method forcontrolling a temperature of a working fluid, comprising: directing, byat least one coil segment, working fluid from an inlet header to anoutlet header in a heat exchanging device; determining, by a controlunit, a temperature of the working fluid in the outlet header; andpropelling, by at least one propeller, subsea water across the at leastone coil segment to control the temperature of the working fluid in theoutlet header.
 11. The method of claim 10, further comprisingactivating, by the control unit, the at least one propeller when thedetermined temperature of the working fluid in the outlet header isoutside a determined temperature range.
 12. The method of claim 10,further comprising: determining, by the control unit, a temperature ofthe subsea water; comparing the temperature of the subsea water with thetemperature of the working fluid in the outlet header; and activatingthe at least one propeller when the temperature of the subsea water isless than the temperature of the working fluid in the outlet header. 13.The method of claim 12, further comprising deactivating the at least onepropeller when the temperature of the subsea water is greater than thetemperature of the working fluid in the outlet header.
 14. The method ofclaim 10, further comprising: encapsulating a nozzle around the at leastone propeller; and directing, by the nozzle, flow of the subsea watertowards the at least one coil segment.
 15. A system, comprising: aninlet header; an outlet header; a plurality of coil segments disposedbetween the inlet header and the outlet header and configured to directa working fluid from the inlet header to the outlet header; and aplurality of propellers disposed proximate to the plurality of coilsegments and configured to propel subsea water across the plurality ofcoil segments so as to control a temperature of the working fluid in theoutlet header.
 16. The system of claim 15, further comprising a controlunit operatively coupled to the plurality of propellers and configuredto activate or deactivate each of the plurality of propellers toregulate a flow of the subsea water across the plurality of coilsegments.
 17. The system of claim 15, wherein the control unitcomprises: a first sensor operatively coupled to the outlet header andconfigured to determine the temperature of the working fluid at adetermined location in the outlet header; and a processing subunitelectrically coupled to the first sensor and the plurality of propellersand configured to activate or deactivate one or more propellers in theplurality of propellers based on the determined temperature of theworking fluid.
 18. The system of claim 17, wherein the control unitfurther comprises a second sensor operatively coupled to the processingsubunit and configured to determine a temperature of the subsea water.19. The system of claim 18, wherein the processing subunit is configuredto: compare the temperature of the subsea water with the temperature ofthe working fluid in the outlet header; and activate one or morepropellers in the plurality of propellers when the temperature of thesubsea water is less than the temperature of the working fluid in theoutlet header.
 20. The system of claim 19, wherein the processingsubunit is configured to deactivate one or more propellers in theplurality of propellers when the temperature of the subsea water isgreater than the temperature of the working fluid in the outlet header.21. The system of claim 15, further comprising a plurality of nozzles,wherein each of the plurality of nozzles encloses a correspondingpropeller and is configured to direct the flow of the subsea watertowards at least one coil segment of the plurality of coil segments.